A coil constituted by a wound wire is typically formed on a magnetic pole of a multi-pole armature. As a conventional method of forming the coils, as disclosed in JP 2000-245120 A, a method using a device called an inserter has been known. Further, as disclosed in JP 2003-169455 A, there has been known a method of causing a nozzle, which is capable of feeding a wire, to circle around each magnetic pole so that the wire fed from the nozzle is directly wound around the magnetic pole. In the method using the inserter as disclosed in JP 2000-245120 A, while the wire previously wound into a ring shape is pulled from one end portion of the multi-pole armature in an axial direction thereof, the wire is inserted into slots formed between the magnetic poles. Finally, the wire wound into a ring shape is fitted onto the magnetic pole of the multi-pole armature.